If I were a CISO for a publicly traded company I would implement the following protections.

Secure lines of communication – depending on what goods we’re trading can determine the security threat. Things such as oil or gold would definitely need a secure line that can’t just be tapped into by anyone.

Data backups/secure data- This is another big one as a lot of cyber attacks leave important data deleted. I would do my best to prevent that from happening by having some sort of protection inaccessible by most  

PLAN B – I would also formulate a way to keep the gears turning if there was ever a successful attack. A full stop to a trading company could cost so so much